Since γδ T cells utilize TNF-related apoptosis inducing ligand (TRAIL) for killing of tumor cells in addition to granzyme B and perforin, we investigated the role of the TRAIL-/TRAIL-R system in γδ T cell-cytotoxicity toward pancreatic ductal adenocarcinoma (PDAC) and other cancer cells. The gene discussed is PRF1; the disease is pancreatic ductal adenocarcinoma.